Induction melting furnace



March 12 1957 R. s. sEGswoTl-l 2,785,214

INDUCTION MELTING FURNACE Inventor Roar/er s. sfcswoRrH March 12 1957 R.s. sEGswoRTH j Inventor 2 Sheets-Sheet 2 ROBERT S. SECSWORTH Attyssupport for the coil.

United States Patent O NDUCTION MELTIN G FURNACE Robert SidneySegsworth, Toronto, Ontario, Cana'daz assignor to The GeneralEngineering Company Limited, Toronto, Ontario, Canada Application June8, 1955, Serial No. 514,046

Claims. (Cl. 13-27) This invention relates to improvements in inductionmelting furnaces.

Heretofore, when an induction melting furnace has been employed formelting various materials, it has been the practice to change cruciblesbetween melts of different materials. Crucibles have the disadvantage ofbeing more expensive and less rugged than fixed rammed linings.

It is the main object of the invention to provide an iniproved inductionmelting furnace characterized by a removable rammed lining whereby thesame flexibility of change of melting pot is achieved as with crucibles.

It is another object of the invention to provide an improvedconstruction of induction melting furnace embodying an embedded fixedinduction heating coil.

v It is a further object of the invention to provide an inductionmelting furnace embodying improved tilting mechanism.

Other objects of the invention will be appreciated from a study of thefollowing specification taken in conjunction with the accompanyingdrawings.

In the drawings:

Figure l is a sectional elevation view of the improved induction meltingfurnace of the invention;

Figure 2 is an elevation of the induction melting furnace of theinvention;

Figure 3 is a view of the device of Figure 2 but showing'the furnace indumping motion; and

Figure 4 is a view of the device of Figure 2 showing the furnace in fulldumping position.

Referring to the drawings, the furnace structure of v.the inventioncomprises the tiltable furnace box 10 supported on the base structure11. Preferably, non-magnetic material is used throughout. Where metal isrequired, bronze or other non-magnetic metal is used. Otherwise,asbestos board or like rigid insulating material such as is known in thetrade by the name Transite, is employed in the construction.

The outer furnace box 10 is built up of rigid insulating board to formthe bottom wall 13 and front and rear walls 14 and 15, the side wallsthereof not being shown in Figure 1. An induction heating coil 16 isformed of a plurality of turns of copper tubing 17, the ends 18 and 19of which extend through openings 20 and 21 in the rear wall to terminalblocks 22 and 23. The induction coil 16 is held rigidly in place bymeans of a mixture of a light weight castable refractory material suchas Portland cement and expanded mica particlesknown by the nameVermiculite. The mixture is cast around the coil while in the innerfurnace box 12 to provide thermal and electrical insulation as well asmechanical l The inside surfaces 24 of the coil are then covered with alayer of refractory cement reinforced by a single layer of asbestoscloth applied therewith to form a coil lining 25.

A conventional crucible (not shown) may be set into the coil to be usedas a melting pot. The space between "ice the Crucible and coil liningmay be packed with an appropriate insulating material.

It is preferred, however, to form a melting pot 26 by inserting a thinmetallic former 27 around which a refractory material 28 may be rammed.A dry ramming refractory mix containing a small amount of sodiumsilicate and moisture is employed for forming the pouring lip 29. Themetallic former 27 may be washed out with the first melt. It ispreferred, however, to employ a former having a slight inward taper andto coat it with paraffin to enable removal after ramming prior toundertaking a melt in the pot so formed. Power may be applied for ashort time to facilitate the removal of such a tapered liner. Theflexibility thus afforded in pot shape, not removal and replacement isreadily apparent to skilled persons in contrast with the size and shapelimitations of crucibles. Moreover, a rammed pot is serviceable tohigher temperatures in general than a corresponding7 crucible.

The inner furnace box 12 containing the coil 16 and pot 26 is removablymounted in the outer furnace box 10. The latter comprises the bottomwall 13, side walls 30, front and rear walls 14 and 15 and the topretaining panel 31. The walls of both the inner and outer furnace boxesare held in assembly by means of bronze screws 32 and 33 at the walljoints. A stop 34 held by bronze screw 35 retains the inner furnace boxin spaced relation to the rear wall 15 to permit introduction of waterconducting power leads 36 for fixture to terminals 22 and 23. The leads36 are clamped by a clamping block 37 to the outer edge of the bottomwall 13 by bronze bolts 37a.

The base structure 11 and tipping apparatus is shown in more detail inFigures 2 to 4. The bottom wall 13 of the outer furnace box 10 issupported by the forwardly located primary fulcrum bracket 38 on thepivot pin 39 in support 40 of platform 41. Two fulcrum arms 41a riseforwardly and upwardly from a base plate 42 on either side of the outerfurnace box as at 48 near below the lip in the region of the front panel14.

fn operation, the cylinders 43 in their retracted position, support theouter furnace box 10 substantially in an upright position by means ofthe pivotal connection 49 of their piston arms 50 to the side mountingbrackets 51 of box 10. Actuation of the pressure cylinder causes outwardextension of their pist-on arms causing initial tipping of the box 10and furnace, therein, on primary fulcrum bracket 38 about pivot pin 39,as shown in Figure 3. Figure 4 illustrates final or secondary tippingmotion of the box 18 on the `secondary fulcrum pins 47 upon moving intoregistry with the sockets 46 of the fulcrum arms 41a. Notice IthatIsockets 46 are spaced a distance from the pivot pin 39 equal to theradius -of the forwardly extending socket slot 52 of primary fulcrumbracket 38 wherein the said radius is described from the secondaryfulcrum pins 47.

it will be Iapparent that 'any well-known source of pressure medium maybe employed for actuating the pressure cylinders. While it is desiredthat the apparatus shown be 4constructed so that single acting pressurecylinders only are required wherein the furnace box 10 returns to theupright position under action of gravity, double acting cylinders mayalso be employed.

It is contemplated that a plurality of inner furnace boxes eachcontaining the induction heating coil and rammed lining may be kept onhand to provide `an even greater flexibilitty of operation. The innerfurnace box is readily removed by removal of the top retaining panel ofbox 10.

It is intended that alternatives and modifications falling Within thescope of ordinary skill in the art shall be embraced by the presentdisclosure which sets forth the preferred practice of the invention.

What l claim as my invention is:

1. An'induction melting furnace comprising: afurnace box having an open`end and formed from a rigid heat insulating material; aninductionheating coil in said box spaced fromthe walls thereof; an insulatingcement between said coil and saidwalls rigidly supporting said coil inVsaid box; and la removable rammed refractory melting pot form-ed withinsaid coil and serving as a removable lining forsaid furnace.

2. Au induction melting furnace comprising: a furnace box having 'anVopen end 'and formed from a rigid heat insulating material; aninduction heating coil in said box spaced'fromfthe 'wallsthereof; aninsulating cement between said coil -and said walls rigidly supportingsaid coil in said box; a refractory material rammed to a shape deliningwithin said-coil melting pot; and an outer furnace box having side wallsformed of a rigid insulating maieri-al' designed removably to mount saidrst, mentioned furnace box.

3. An induction melting furnace comprising: a furnace ybox having anopen end and formed from la rigid heat insulating material; anim-ductionheating coil in said box 'spaced from the walls thereof; an insulatingcement between said Vcoil and said walls rigidly supporting said coil insaid box; a Vrefractory material rammed to a shape dewithin said coilVaV melting pot; a lining of 'asbestos cloth extending over the innerSurfaces of .said coil between said coil and said rammed refractorymaterial; and an louter furnace box having side walls formed of Ia rigidinsulating material. designed removablyto mount said first mentionedfurnace box.

4. An induction melting-furnace comprising: a furnace box having an openendend formed from a rigidV heat insulating material; .aninduction.heating coil in said box spacedfrom thewalls thereof; lan insulatingcement between said coil and said Walls rigidly supporting said coil in.said 'box; a refractorymaterial rammed to a shape erung within saidcoil a. melting pot; a metallic former defining the inner .side wailsurfaces of said melting pot 'and Yadaptedito be removed therefrornbymelting; and

hrst mentioned furnace box. v

5. An induction melting furnace comprising: a furnace box ha' ing anopen end and formed from a rigid heat insulating material; an inductionheating coil in said box spaced from the walls thereof; an insulatingcement between said coil and said walls rigidly supporting said coil insaid box; a refractoryrmaterial .rammed to `a shape-defining within saidcoil a melting pot; an outer furnace box having side walls formed of arigid insulating material designed to removably' mount said 'firstmentioned furnace box; primary fulcrum means mounting said outer furnacebox for tipping motion; and a pressure cylinder supporting said outerfurnace box on said primary fulcrum means in a melting position anddesigned to move said outer furnace box on said primary fulcrum meanstoward a pouring position.

6. An induction melting Ifurnace comprising: 'a furnace box having yanopen end and formed from a rigid heat insulating material; an inductionheating coil in said box spaced from the walls thereof; an insulatingcement between said coil and said walls rigidly supporting said coil insaid box; la refractory material rammed to a shape defining within saidcoil a melting pot; a pouring spout extending 'beyond said coil andlsaid furnace box at the open end thereof; and an outer furnace boxhaving side walls formed of la rigid insulating material designedremovably to mount sai-d rst mentioned furnace box.

7. An induction melting furnace comprising: a furnace box having an openend and formed from a rigid heat insulating material; an inductionheating coil in said box spaced from the Walls thereof; an insulatingcement between said coil and said Walls rigidly supporting said coil insaid box; a refractory material rammed to a shape defining Within saidcoil a melting pot; a pouring spout extending beyond said coil and saidfurnace box at the open end thereof; an outer furnace box having sidewalls formedV of a rigid insulating material designed to removably mountsaid rst mentioned furnace box; primary fulcrum means mounting saidouter furnace boxfor tipping motion; and a pressure cylinder supportingsaid outer furnace box on said primary fulcrum means in a meltingposition and designed to move said outer furnace boxv on said primaryfulcrum means toward a pouring position.

v8. An induction melting .furnace comprising: a furnace box having anopen end and formed from a rigid heat insulating material; an inductionheating coil `in said box spaced from the walls thereof; an insulatingcement between said Vcoil .and said walls rigidly supporting said coilin said box; a refractory material rammed to a shape defining Withinsaid coil a melting pot; a pouring spout extending beyond said coil andsaid urnace box at lthe open end thereof; an outer furnace box havingside Walls formed of a rigid insulating material designed to removablymount said first mentionedfurnace box; primaryfulcrum means mountingsaid outer furnace box for tipping motion; aapressure cylindersupporting said outer furnace box on said primary fulcrum means in amelting position and designed to move said outer furnace box on saidAprimary :fulcrum means toward a pouring position; and

Vheating coil supported in internal spaced `relation in said innerfurnace box; and a refractory cement rigidly supporting said coil insaid inner furnace box.

l0. An induction furnace comprising; an ,outer furnace box formed ofslabs or rigid insulating material; a a support for said box includingtilting mechanism therefor formed of substantially. non-magneticmaterial;` a removable Vinner furnace box supported in said outerbox andformedof a rigid heat-insulating material; an inductionheating coilsupported in internal spaced relation lin said inner furnace box; arefractory Vcement rigidly supportingV said coil in said inner furnaceboxzend a rammed refractory material defining a melting pot within saidcoil.

References Cited in the le of this patent UNITED STATES PATENTS

